In this question says:

An adult human has been estimated to have some 60,000 miles (96,560 km) of capillaries with a total surface area of some 800–1000 m2 (an area greater than three tennis courts).

But the question is about the length and only mentions area in the body not the title, and the answers don't cite the area.

  • $\begingroup$ Does the Coastline paradox affect this? $\endgroup$
    – Andrey
    Oct 17, 2016 at 3:37
  • $\begingroup$ Friction? Drag in blood vessels is much more complex than friction... $\endgroup$
    – Aron
    Oct 17, 2016 at 11:00
  • $\begingroup$ @Aron Ok, but maybe I can calculate a lower bound. $\endgroup$ Oct 17, 2016 at 13:37
  • $\begingroup$ @Andrey Very interesting point. To that I can answer this: imagine a blood vessel section of 0.1 meter long, and 0.01 meter in "average diameter" (that needs to be estimated. Then you say the surface area corresponding of that section of the circulatory system is the area of the abstract cilinder we use to represent it. Also, if we specify the ruler size, the area becomes more well defined (althought still subjective a little). $\endgroup$ Oct 17, 2016 at 13:43
  • $\begingroup$ Friction is a very bad word to describe it. But the simplest way to estimate the drag is to use Newton's 3rd. The drag is equal to the force on the blood, assuming the blood is at a steady speed. Figure out how hard the heart pushes. $\endgroup$
    – Aron
    Oct 17, 2016 at 15:58


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